We plan to exploit newly developed possibilities to learn about the machinery of synaptic transmission by use of the neuromuscularjunction on the ceratomandibularis muscle of the lizard. We plan to use focal extracellular recordings and patch clamps at the terminal boutons of the nerve ending to: 1) determine the type (or types) of calcium channels and their location 2) determine the relationship between calcium current and transmitter release 3) determine the relationship between the sub-membrane Ca concentration and transmitter release 4) identify a putative Na-Ca exchange current 5) look for evidence of vesicular fusion by video contrast enhancement and image processing 6) test for insertion of new channels by fusion of vesicles into the surface membrane of the bouton. We will simulate our experiments with a powerful new computer program in order o gain insight into our interpretations of the currents, Ca concentration profiles, and vesicle fusion machinery.